Objective: Conduct a systematic review and meta-analysis of randomized controlled trials (RCTs) evaluating the efficacy of individual humanistic-experiential therapies (HEPs) for depression.
Method: Database searches (Scopus, Medline, and PsycINFO) identified RCTs comparing any HEP intervention with a treatment-as-usual (TAU) control or active alternative intervention for the treatment of depression. Included studies were assessed using the Risk of Bias 2 tool and narratively synthesized. Post-treatment and follow-up effect sizes were aggregated using random-effects meta-analysis and moderators of treatment effect were explored (PROSPERO: CRD42021240485).
Results: Seventeen RCTs, synthesized across four meta-analyzes, indicated HEP depression outcomes were significantly better than TAU controls at post-treatment (g = 0.41, 95% CI [0.18, 0.65], n = 735), but not significantly different at follow-up (g = 0.14, 95% CI [-0.30, 0.58], n = 631). HEP depression outcomes were comparable to active treatments at post-treatment (g = -0.09, 95% CI [-0.26, 0.08], n = 2131), but significantly favored non-HEP alternative interventions at follow-up (g = -0.21, 95% CI [-0.35, -0.07], n = 1196).
Conclusion: Relative to usual care, HEPs are effective in the short-term and comparable to non-HEP alternative interventions at post-treatment, but not at follow-up. However, imprecision, inconsistency, and risk of bias concerns were identified as limitations of the evidence included. Future large-scale trials of HEPs with equipoise between comparator conditions are required.
Keywords: depression; humanistic-experiential therapies; meta-analysis; process-guiding; randomized controlled trial; systematic review.